1984 90hp mercury boat motor problems?

Question

I just acquired a boat that has a 1984 mercury 90hp motor on it SN:6572297 and it doesn't seem to want to rev out all the way. When i have the boat floored the motor revs to ~4300rpm and it seems like it's running at about 3/4 throttle and i think it should be running to something like 6000rpm. I checked the throttle cables and they seem to be adjusted correctly. The butterflies on the carbs are also opening all the way. When i have it floored it seems to run great though just not to its full potential. What should I check?

Thanks,

Nick

Answer 1

if your motor has power trim, try triming the motor up some with it at full throttle, you will probally increase your rpms 800 to 1000, however if it is an inline six 90 hp mercury, i don't suggest running it over 5100 rpms anyway, the inline six is a great motor and will last you forever if you keep the rpms below 5100. hope this helps.